chemistry chp ter 9

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Chapter 9 Manufacture Substances in Industry

Sulphuric Acid (H4SO4)

USES OF SULPHURIC ACID

Produce chemical fertilizer (NH4)2SO4& K2SO4. Soluble in water & can beabsorbed by plant.

Car batteries is used as the electrolyte.

Used in the making of artificial silk-like fibres & rayon.

Chemical like paints, dyes & drug as one of their component materials.

MANUFACTURE OF SULPHURIC ACID

Sulphuric acid is manufactured in industry through contact process The process contain 3 stage

STAGE1:Production Of Sulphur Dioxide from Sulphur

i. Combustion of sulphur or sulphide ores in the air produce sulphur dioxide SO2.

S(s)+O2(g) SO2(g)sulphur

ii. Sulphur dioxide is dried and purified.

STAGE2: Production Of Sulphur Trioxide From Sulphur Dioxide

i. The purified sulphur dioxide SO2 and excess air are passed over vanadium(V)oxide V2O5 at controlled optimum condition optimum condition to producesulphur trioxide SO3.

2SO2(g)+O2(g) 2SO3(g)

ii. The optimum used area) Temperature:450-500Cb) Pressure: 2-3 atmospheresc) Catalyst: Vanadium(V) oxide

iii. Under controlled optimum conditions, 98% conversion is possible. Sulphur dioxide& oxygen that have not reacted are allowed to flow back again over the catalystin the converter.

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STAGE3: Conversion of trioxide to sulphuric acid

i. Sulphur trioxide SO2 is dissolved in concentrated sulphuric acid H2SO4 to formoleum H2S2O7 which is then diluted with water to form sulphuric acid H2SO4.

SO3(g)+H2SO4(l) H2S2O7(l) Oleum

H2S2O7(l)+ H2O(l) 2H2SO4(aq)

ii. The 2 reactions are equivalent to adding sulphur trioxide directly into H2O.

SO3(g)+H2O(l) H2SO4(aq)

iii. The addition of sulphur trioxide directly into is not carried out because thereaction is vary vigorous/a lot of heat is given off. As a result, a large cloud of

sulphuric acid fumes is produced, which is corrosive and causes air pollution.

In the converter

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Sulphur Oxygen

S(s) +

O2(g)SO2(g)

SO2(g)+H2SO4(aq)H2S2O7(l)

H2S2O7(l) H2O(l)2H2SO4(aq)

2SO(g) + O2(g) 2SO3(g)Temperature: 450-500C

Pressure: 2-3 atmospheresCatalyst: Vanadium(V) oxide

Oxygen

Unreacted

2% SO2 isflowed back

to convertertogether with O2

The Contact Process

Outline Of Contact process


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SULPHUR DIOXIDE & ENVIRONMENTAL POLLUTION

Colourless & poisonous gas with a vary pungent smell.

Sulphur dioxide escape into the air causes air pollution.

It is an acidic dissolves in H20 to form Sulphurous,H2SO3.At atmosphere,sulphur dioxide dissolve in water droplets to form sulphurous acidic.

SO2(g) + H2O(l) H2SO3(aq)

Oxidation of sulphur acid by O2 produce sulphuric acid,H2SO4, as acid rain.Sulphur trioxide = easily oxidised in the air to form sulphur trioxide. Sulphurtrioxide dissolve in rainwater to produce sulphuric acid.

SO3(g) + H2O(l) H2SO4(aq)

AMMONIA & ITS SALTS(NH3)

USES OF AMMONIA

In the manufacture of chemical fertilizers such as ammonium sulphate,

ammonia nitric, ammonia phosphate & urea. To manufacture nitric acid & explosive.

In the making of synthetic fibre & nylon.

As a degreasing agent in [aq] form to remove greasy stains in the kitchen.

PROPERTIES OF AMMONIA GAS

It colourless & has a pungent odour. It is vary soluble in water & form a weak alkaline solution.

It less dense than water.

It easily liquified (at about 35.5C) when cool.

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a) Ammonia gas dissolves in water to form a weak alkali.

NH3(g) + H2O(l) NH4+(aq) + OH-(aq)

b) The presence of hydroxide icon causes the aqueous solution to become alkaline.

i. Turns red litmus paper blue.ii. Reacts with acid to form only salt & water in neutralization reaction.

NH3(aq) + HCI(aq) NH4CI(aq)

2NH3+ H2SO4(aq) (NH4)2SO4(aq)

iii. Reacts with solution of metallic cations to produce precipitates.

Fe+(aq) + 2OH(aq) Fe (OH)2(s) (Form ammonia solution) Dirty green precipitate

MANUFACTURE OF AMMONIA IN INDUSTRY

Manufacture on a large scale through the haber process. In this process, ammonia is formed form direct combination of nitrogen &

hydrogen gas in the volume ratio 1:3.

The gas nitrogen obtain form the fractional distillation of liquefied air. Thehydrogen gas is obtained form the cracking of petroleum/from the catalysedreaction of natural gas, CH4, with steam.

CH4(g) + H2O(g) CO(g) + 3H2(g)

The mixture of nitrogen and hydrogen gases is passed over an iron catalyst

under controlled optimum condition as below to form ammonia gas.

Temperature: 450-500C

Pressure: 200-500 atmospheres

Catalyst used: Iron fillings

N2(g) + 3H2(g) 2NH3(g)

Under these control optimum condition, only 15% of the gas mixture turn into

ammonia gas. The nitrogen and hydrogen that have not reacted are then flowback over the catalyst again in the reactor chamber.

The ammonia product is then cooled at a low temperature so that it condensesinto a liquid in the cooling chamber.

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AMMONIUM FERTILIZERS

1. Nitrogen is required in large amount by plant to make proteins which arenecessary for growth and cell repair.

2. Most plant are not able to get a nitrogen supply directly from the air althoughit is abundant in the air (78%). Plants can only absorb soluble nitrogencompounds from soil through their roots.

3. The nitrogen compounds are usually soluble nitric salt, ammonia and ammoniasalt which are manufacture as chemical fertilizer.

4. Reactions of ammonia with acids produce ammonium fertilizers.

NH3(aq) + HNO3(aq) NH4NO3(aq)Ammonium nitrate

3NH3(aq) + H3PO4(aq) (NH4)3PO4(aq) Ammonium phosphate

2NH3(aq) +H2SO4(aq) (NH4)2SO4(aq) mmonium sulphate

ALLOYS

ARRANGEMENT OF ATOMS IN MATELS

1. The atom of pure metals are packed together closely. This causes the metal tohave a hight density

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Nitrogen Hydrogen

N2 and H2 are mixed in the proportion of

1:3N2(g) + 3H2(g) 2NH

3(g)

Temperature: 450-500CPressure: 200-500

atmospheresCatalyst used: Iron fillings

Liquid

ammoniaIn cooling chamber

Unreacted N2 and H2gases

In the reactor chamber

Outline Of Haber process


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2. The forces of attraction between atoms (metallic bonds) are strong. More heatenergy is needed to overcome the metallic bond so that the atoms are furtherapart during the melting. This is why metals usually have hight melting point.

3. Heat energy can be transferred easily from one atom to the next by vibration.This make metal good conduct of heat.

4. The freely moving outermost electrons within the metals structure are able to

conduct electricity. Metal are, therefore, good electrical conductors.

5. Since atoms of pure metal are of the same size, they are arranged orderly in aregular layered pattern. When a force is applied to metal, layer of atom slideeasily over one another. This make pure metals soft, malleable and ductile.

Pure metal = too soft, low resistance to corrosion, rush & tarnish easily.

Improve the physical properties of metal, a small amount of another element(usually metal) is added to form another an alloy.

An alloy = mixture of two/more metals (non-metal) in a specific proportion.

For example:a. Bronze (90% of copper and 10% of tin)b. Steel (99% of iron and 1% of carbon)

The purposes of making alloys include the following:a) Increase the strengthi. Pure iron= soft and vary malleable. A small amount of carbon is added to

iron steal is formed. The more carbon is added, the stronger the steel

becomes.

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Force

Layer of atom slide

Metals are ductile

Force

The shape of the metal

change

Metal are malleable


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ii. Pure aluminium is light but not strong. A small amount of copper &magnesium are added to aluminium, a strong, light & durable alloy call

duralumin is produced.b)Improving the resistance to corrosion

i. Iron rust easily but stainless steel which contains 80.6% of iron, 0.4% of

carbon, 18% of chromium & 1% of nickel does not rush. These propertiesmake stainless steel suitable for making surgical instrument and cutlery.

ii. Pure copper tarnish easily. When zinc (30%) is added, the yellow alloywhich is known as brass develops a high resistance to corrosion.

c)Enhancing the appearance

i. Pewter, an alloy of tin (97%), antimony and copper is not only hard but alsohas a more beautiful white silvery appearance.

ii. When copper is mixed with nickel to form cupronickel, an alloy that has anattractive silvery, bright appearance is formed which is suitable formaking coins.

Alloy Composition Properties Uses

High carbon steel 99% iron1% carbon

Strong,hard and highwear resistance

Making of cuttingtools, hammers andchisels

Stainless steel 80.6% iron0.4% carbon

18%chromium1% nickel

Do not rust andtarnish, strong and

durable

Making of surgicalinstrument, knivesforks and spoons

Brass 70% copper 30% zinc

Hard, do not rust,bright appearance

Making ofornaments, electricalwiring and plug.

Bronze 90% copper 10% tin

Hard, do not corrodeeasily and durable

For casting bells,medals, swords andstatues

Pewter 90% tin2.5% copper

0.5% antimony

Ductile and malleable,white silveryappearance

Making ofornaments,souvenirs and mugs

Duralumin 95% aluminium4% copper

1%magnesium

Light, strong anddurable

Making part ofaircrafts and racingcars

Cupronickel 75%copper 25%nickel

Attractive, silveryappearance, hard and

tough

Making of silvercoins

Composition, properties and uses of alloys

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The formation of alloy

Synthetic Polymers

Polymer = large number of small identical/similar units joined together repeatedly.

Monomer = smaller molecules that make up the repeating unit in polymer.

Polymerisation = process of joining together a large number of monomers to forma long chain polymer.

Polymer can be naturally occurring/man-made(synthetic).

Natural polymer = found in plant & in animals(starch cellulose, protein & rubber).

2 type of polymerisation in producing synthetic polymer are add. polymerisation.

Double bonds between two carbon atoms usually undergo add. polymerisation.

Some Common Addition Polymers

Name(s) Formula Monomer Properties Uses

Polyethylenelow density (LDPE)

(CH2-CH2)nethyleneCH2=CH2

soft, waxy solidfilm wrap, plasticbags

Polyethylenehigh density (HDPE)

(CH2-CH2)nethyleneCH2=CH2

rigid, translucentsolid

electrical insulationbottles, toys

Polypropylene(PP) different grades

[CH2-CH(CH3)]n

propyleneCH2=CHCH3

atactic: soft, elasticsolidisotactic: hard, strongsolid

similar to LDPEcarpet, upholstery

Poly(vinyl chloride)(PVC)

(CH2-CHCl)nvinyl chlorideCH2=CHCl

strong rigid solidpipes, siding,flooring

Poly(vinylidenechloride)(Saran A)

(CH2-CCl2)nvinylidenechlorideCH2=CCl2

dense, high-meltingsolid

seat covers, films

Polystyrene

(PS)

[CH2-

CH(C6H5)]n

styrene

CH2=CHC6H5

hard, rigid, clear solidsoluble in organic

solvents

toys, cabinetspackaging

(foamed)

Polyacrylonitrile(PAN, Orlon, Acrilan)

(CH2-CHCN)n

acrylonitrileCH2=CHCN

high-melting solidsoluble in organicsolvents

rugs, blanketsclothing

Polytetrafluoroethylene(PTFE, Teflon)

(CF2-CF2)ntetrafluoroethyleneCF2=CF2

resistant, smoothsolid

non-stick surfaceselectrical insulation

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Poly(methylmethacrylate)(PMMA, Lucite,Plexiglas)

[CH2-C(CH3)CO2CH

3]n

methylmethacrylateCH2=C(CH3)CO2CH3

hard, transparentsolid

lighting covers,signsskylights

Poly(vinyl acetate)

(PVAc)

(CH2-

CHOCOCH3)n

vinyl acetate

CH2=CHOCOCH3

soft, sticky solid

latex paints,

adhesives

cis-Polyisoprenenatural rubber

[CH2-CH=C(CH3)-CH2]n

isopreneCH2=CH-C(CH3)=CH2

soft, sticky solidrequiresvulcanizationfor practical use

Polychloroprene(cis + trans)(Neoprene)

[CH2-CH=CCl-CH2]n

chloropreneCH2=CH-CCl=CH2

tough, rubbery solidsynthetic rubberoil resistant

Uses of synthetic polymers

1. Advantages

a. cheap, light-weight & translucent.b. easily coloured, easily moulded & shaped.c. non-corrosive, waterproof & good insulator.d. durable & long lasting [resistant to decay, rusting & chemical attacks].

2. Disadvantagea. Flammable

When a synthetic polymer material catches fire, poisonous fumes areproduce causing air pollution.

b. Non-biodegradable

When discharge, they cause litter problem and pollute the environment.

c. Plastic container that are left aside in an open area collect rainwater whichbecomes the breeding ground for mosquitoes.

d. There are limitation in recycle have to be separated out as the addition ofnon-recyclable polymers in the mixture affect the properties of the

recycled polymers.

Glass and Ceramics

Glass

a. Transparent, hard but brittle.b. A heat & electric insulator.

c. Resistant to corrosion.d. Chemical not reaction & resistant to chemical attack.

e. Easy to maintain.

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Type of glass Composition Properties Uses

Fused glass SiO2: 100% Transparent

High melting point

Good heat insulator

Lens

Telescope mirrors

Laboratory apparatus

Soda-lime glass SiO2: 75%Na2O:15%

CaO: 9%Other:1%

Low melting point,easily molded into

desired shape andsize

Low resistant tochemical attacks

Brittle

Drinking glass,bottles

Electric bulbs Window glass

Borosilicate glass SiO2: 78%B2O3: 12%Na2O: 5%CaO: 3%Al2O3:2%

Resistant chemicalattack and durable

High melting point

Good insulator toheat

Cooking utensils

Laboratory glasswaresuch as conical flaksand boiling tube

Lead crystal glass (flintglass)

SiO2: 70%Pbo/PbO2:20%

Na2O: 10%

High refractive index

High density

Attractive glitteringappearance

Lenses and prisms

Decorative glasswareand art object

Imation jewellery

Ceramics

Traditional silicate ceramics = heating aluminosilicate clay [kaolin] at high temp.

Special properties :a. Hard, strong but brittleb. Have high melting point & remain stable at high tempc. Heat & electric instrument

d. Resistant to corrosion & weare. Chemically not reactive

f. Do not readily deform under stress

Ceramic uses :

a. Construction materialsi. Strong & hard = make roof tiles, bricks cement, sinks & toilet bowls.

ii. Make refractory bricks because high resistant to heat.b.Decorative items

i. Make pottery, plates & porcelain vases [do not tarnish easily & durable].ii. Make bathroom fixture such as floor & wall tiles.

c. Electrical insulatori. Make electrical insulator [toasters, fridges & electrical plug].

Materials Melting point/ C Density/G cm-3 Elastic modulus/GPa

Hardness/ mohs

Oxide ceramicAlumina,AL2O3Beryllia, BeO

20542574

3.973.01

380370

98

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Zirconia, ZiO 2710 5.68 210 8

Non-oxideceramicsBoroncarbide,B4C3Silicon nitride,

Si3, n4

23502830

1900

2.503.16

3.17

280400

310

99

9MetalsAluminiumSteel

6601515

2.707.86

70205

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Composite Materials

1. A composite materials (or composite) is a structure of materials that is formedby two or more different substances such as metal, glass, ceramic and polymer.

2. Some common composite materials are:

a.Reinforces concreteb.Superconductorc.Fibre optic

d.Fibre glasse.Photochromic glass

Reinforces Concrete

1. Concrete is hard, fireproof, waterproof, comparatively cheap and easy tomaintain. It is more important construction materials.

2. The reinforces is a combination of concrete and steel.

Supercondutors1. Metal such as copper and aluminium are good conductor of electricity, but 20% of

the electric energy is lost in the form of heat during transmission.2. Super conductor are materials that have no resistance to the flow of electricity

at a particular temperature. Hence, 100% electricity transmission is possible.3. One of the most dramatic properties of a superconductor is its ability to levitate

a magnet. Superconductor are used to build magnetically levitate high-speed train(at about 552 km/h).

4. Superconductor are used to make chips for smaller and faster supercomputer.Superconductor also play an important role in high speed data processing ininternet communication.

Fibre Optic1. Fibre optic is a composite material that in used to transmit signals for light wave.

2. Fibre optic is used in

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a. Telecommunicate where the telephone substation are liked by fibre opticcables.

b. Domestic cable television networkc. Closed circuit television security system.

3. Fibre optic also used in medical fields. It is used in a number of instrument which

enable the investigation for internal body part without having to perform surgery.

Fibre Glass1. Fibre glass is glass in the form of fine threads. Molten gas is dropped onto a

refractory rating disc when the glass flies off the disc glass to form fibre.

2. Fibre glass is strong than steel, do not burnt, stretch or rot, resistant to fire andwater but is brittle.

3. When fibre glass added to a plastic, a new composite material fibre glassreinforces plastic is formed.

4. Fibre glass reinforces plastic has more superior properties than glass and plastic.

It isa. Extremely strongb. Light weigh

c. Resistant to fire and waterd. Can be molded, shaped and twisted

Photochromic Glass1. When 0.01 to 0.1% of silver chloride (a type of photochromic substances) and a

small amount of copper (II) chloride are added to molten silicon dioxide,photochromic glass is formed.

2. The photochromic glass has a special properties. It darken when exposed to

strong sunlight or ultraviolet.3. Photochromic glass is suitable for making sunglasses.

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chemistry chp ter 9

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